title: Cerebral ischemia-reperfusion-induced autophagy protects against neuronal injury by mitochondrial clearance.
abstract: Cerebral ischemia-reperfusion (I-R) is a complex pathological process. Although autophagy can be evoked by ischemia, its involvement in the reperfusion phase after ischemia and its contribution to the fate of neurons remains largely unknown. In the present investigation, we found that autophagy was activated in the reperfusion phase, as revealed in both mice with middle cerebral artery occlusion and oxygen-glucose deprived cortical neurons in culture. Interestingly, in contrast to that in permanent ischemia, inhibition of autophagy (by 3-methyladenine, bafilomycin A 1, Atg7 knockdown or in atg5(-/-) MEF cells) in the reperfusion phase reinforced, rather than reduced, the brain and cell injury induced by I-R. Inhibition of autophagy either with 3-methyladenine or Atg7 knockdown enhanced the I-R-induced release of cytochrome c and the downstream activation of apoptosis. Moreover, MitoTracker Red-labeled neuronal mitochondria increasingly overlapped with GFP-LC3-labeled autophagosomes during reperfusion, suggesting the presence of mitophagy. The mitochondrial clearance in I-R was reversed by 3-methyladenine and Atg7 silencing, further suggesting that mitophagy underlies the neuroprotection by autophagy. In support, administration of the mitophagy inhibitor mdivi-1 in the reperfusion phase aggravated the ischemia-induced neuronal injury both in vivo and in vitro. PARK2 translocated to mitochondria during reperfusion and Park2 knockdown aggravated ischemia-induced neuronal cell death. In conclusion, the results indicated that autophagy plays different roles in cerebral ischemia and subsequent reperfusion. The protective role of autophagy during reperfusion may be attributable to mitophagy-related mitochondrial clearance and inhibition of downstream apoptosis. PARK2 may be involved in the mitophagy process.
authors.affiliation: Department of Pharmacology; Key Laboratory of Medical Neurobiology of The Ministry of Health of China; Zhejiang Province Key Laboratory of Neurobiology; College of Pharmaceutical Sciences; Zhejiang University; Hangzhou, China.
authors.forename: Xiangnan
authors.initials: X
authors.lastname: Zhang
authors.forename: Haijing
authors.initials: H
authors.lastname: Yan
authors.forename: Yang
authors.initials: Y
authors.lastname: Yuan
authors.forename: Jieqiong
authors.initials: J
authors.lastname: Gao
authors.forename: Zhe
authors.initials: Z
authors.lastname: Shen
authors.forename: Yun
authors.initials: Y
authors.lastname: Cheng
authors.forename: Yao
authors.initials: Y
authors.lastname: Shen
authors.forename: Rong-Rong
authors.initials: RR
authors.lastname: Wang
authors.forename: Xiaofen
authors.initials: X
authors.lastname: Wang
authors.forename: Wei-Wei
authors.initials: WW
authors.lastname: Hu
authors.forename: Guanghui
authors.initials: G
authors.lastname: Wang
authors.forename: Zhong
authors.initials: Z
authors.lastname: Chen
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects; D000071187:Autophagy-Related Protein 5; D000071193:Autophagy-Related Protein 7; D002545:Brain Ischemia / Q000150:complications / Q000473:pathology*; D045304:Cytochromes c / Q000378:metabolism; D019610:Cytoprotection / Q000187:drug effects; D005947:Glucose / Q000172:deficiency; D000860:Hypoxia / Q000150:complications / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D063306:Mitophagy / Q000187:drug effects; D009474:Neurons / Q000187:drug effects / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure; D052999:Quinazolinones / Q000494:pharmacology; D051381:Rats; D015427:Reperfusion Injury / Q000150:complications / Q000473:pathology*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism
chemical_list: C549041:3-(2,4-dichloro-5-methoxyphenyl)-2-sulfanyl-4(3H)-quinazolinone; C495773:Atg5 protein, mouse; C502661:Atg7 protein, mouse; D000071187:Autophagy-Related Protein 5; D008869:Microtubule-Associated Proteins; D052999:Quinazolinones; C025946:3-methyladenine; D045304:Cytochromes c; D044767:Ubiquitin-Protein Ligases; C111567:parkin protein; D000071193:Autophagy-Related Protein 7; D005947:Glucose; D000225:Adenine
keywords: autophagy; cerebral ischemia; mitochondria; mitophagy; neuroprotection